Snap action switch having improved terminal construction



Oct. 22, 1968 J. R. PESVCETTO SNAP ACTION SWITCH HAVING IMPROVEDTERMINAL CONSTRUCTION Filed Nov. 23, 1966 98 INVENTOR. James I?.Pesceffo BY 50a W. @A Hfs Arf'ys United States Patent() 3,407,276 SNAPACTION SWITCH HAVING IMPROVED TERMINAL CONSTRUCTION James R. Pescetto,Chicago, Ill., assigner to Illinois Tool Works Inc., Chicago, Ill., acorporation of Delaware Filed Nov. 23, 1966, Ser. No. 596,515 4 Claims.(Cl. 20G- 67) ABSTRACT OF THE DISCLOSURE Snap action switch having apivoted lrocking element which in turn pivotally supports an over centerspring biased movable contact element. A pushbutton actuator is notchedso as to permit the actuator to pass by one of the fixed terminalelements and Contact the rocking element.

The present invention relates to a new and improved snap action switchdevice, and more particularly, to a single pole double throw snap actionswitch device having improved operating and current carryingcapabilities.

The primary object of the present invention is the provision of a snapaction switch device having excellent contact wiping action with highcurrent carrying capabilities.

Other objects and advantages of the present invention relate to a snapaction switch device which is capable of undergoing a large number ofswitching operations, has a wide range of operating characteristics,offers freedom of design, is made of a minimum number of parts, requireslow operating forces, has a short movement differential or travel ofoperating parts, is easy and economical to fabricate, and is otherwisewell adapted for the purposes intended.

The above and other objects of the present invention are attained by theprovision of a snap action switch device which includes a movablecontact assembly positioned within the switch housing, the movablecontact assembly including a pivotally mounted rocking element which, inturn, pivotally m-ounts a movable contact blade thereto, both of saidrocking element and movable contact blade being biased in one directionby spring means, the arrangement of the above components being such thatboth a horizontal and vertical component of movement is given to themovable contact blade as the movable contact assembly is moved betweenfirst and second position to effect the switching operation desiredwithout employing the spring means as a current carrying member in theswitch circuitry.

Reference is now made to the drawing:

FIG. 1 is a side elevational view of a snap action switch deviceincorporating the features of the present invention;

FIG. 2 is a fragmentary side elevational view showing the position ofthe movable contact assembly after being moved to its second positionfrom that illustrated in FIG. l;

FIG. 3 is an enlarged fragmentary perspective view of the operatingparts of components of the snap action switch device; andV FIG. 4 is afragmentary side elevational view illustrating a modified form of theherein disclosed snap action switch device.

Referring now to the drawing, and first to FIG. l, there will be seen asnap action switch device which can be `characterized as being of thesingle pole double throw variety. The switch 10 includes a switchhousing 12 molded from a suitable plastic material to provide thedesired insulating characteristics, and a suitable cover element (notshown) is provided to cover or close the concavity of the switch housing12. Housing 12 includes apertures 14 for receiving complementaryconfigured lugs associated with the cover element to retain the coverele- ICC ment to the housing 12, and apertures 16 through which may passsuitable means for mounting a plurality of switch devices 10 isjuxtaposed relationship.

A plurality of terminal elements are frictionally mounted to the switchhousing 12, and include first and second spaced terminal elements 18, 20and a common terminal element 22 which is located generally intermediatethereof. Each -of the terminal elements 18, 20` and 22 are positionedadjacent one end thereof within suitably configured elongated slots 24of the switch housing 12 and are held in predetermined attitudes withrespect to one another by projections which are integrally molded to thehousing 12. In the case of the first and second spaced terminals 18, 20,an inwardly directed ear 26 integrally molded to the housing 12 engagesone end of the terminal elements 18, 20 within the c-oncavity of thehousing 12 and cooperates with the elongated slots 24 receiving theterminal elements 18, 20 to maintain them in the position shown in FIG.1 of the drawing. Lug elements 28 also integrally molded to the housing12 may be used as an added means in maintaining the terminal elements18, 20 in the desired predetermined attitude. As to the common terminalelement 22, the upstanding lug portion 30 integrally molded to thehousing 12 within its concavity is adapted to be received within anopening defined by the curved end portion 32 and the tab element 34struck from the common terminal clement adjacent one end thereof tomaintain the terminal element 22 in the position shown in FIG. l of thedrawing.

The terminal elements 18, 20 carry a fixed contact element 36, 38respectively which are located within the concavity of the switchhousing 12 and disposed in spaced and aligned position with respect toone another. The fixed contact elements 36, 38 are adapted to be engagedby a movable contact assrembly 40 which is electrically connected to thecommon terminal element 22 to complete a circuit through either theterminal element 18, the movable contact assembly 40 and the commonterminal element 22 or the terminal element 20, the movable contactassembly 40 and the common terminal element 22. In the form of switchshown in the drawing, the terminal element 18 is normally open, thecircuit being normally closed through the terminal element 20, themovable contact assembly 40 and the common terminal element 22. In thediscussion above, it is assumed that each of the terminal elements 18,20 and 22 are connected to conductors which complete the circuitsdescribed above.

The movable contact assembly 40 includes an L- shaped rocking element42, one end 44 of which is adapted to be received by the angularlyoffset end portion 46 of the common terminal element 22 to permitpivoting or rocking movement of element 42 about a point designated P1in the drawing. As will be discussed hereafter, the arrangement of theparts comprising the movable contact assembly 40 is such that theelement 42 may pivot or rock about the point P1 without becomingdisengaged or displaced from the angularly offset end portion 46 of thecommon terminal element 22.

The other free end 48 of the L-shaped rocking element 42 is curvilinearin configuration and is adapted to be engaged by pu'shbutton means 50 todisplace or rock the L-shaped rocking element 42 about the .point P1 aswill become apparent from the discussion that is to follow.

The L-shaped rocking element includes `a groove 52 along its verticallyextending leg as shown in FIG. 1 for pivotally mounting a movablecontact blade 54. The blade 54 is sharpened at one of its ends 56 toseat in the groove 52 of the L-'shaped rocking element, the other end 58carrying a contact element 60 which is located between 3 the xedcontacts 36, 38 of the terminal elements 18, 20 to perform the desiredswitching operation.

As best seen in FIG. 3 of the drawing, the contact blade 54 isbifurcated and includes a pair of spaced arms 62, 64 and a bight endportion -66 which carries the contact element or button 60. An aperture68 is formed in the bight end portion 60 for anchoring one end of a coilspring 70 which is generally disposed intermediate the spaced arms 62,64 of the contact blade 54. The coil spring 70 extends through anaperture 72 provided in the L-shaped rocking element 42 and is anchoredlat its other end to a spring pivot pin 74 which is xedly mounted to thehousing 12. The coil spring 70 is tensioned between the bight endportion 66 of the movable contact blade and the spring pivot pin 74 tomaintain the various parts of the movable contact assembly 40 in theposition shown in FIG. 1. Specifically, the arrangement of the parts inthe movable contact assembly 40 is such that the coil spring 70 impartsboth a horizontal and a vertical component upon the L-shaped rockingelement 42 holding the end 48 of the L-shaped rocking element 42 incontact with the pushbutton means 50 as Well as positioning the end 44of the L-shaped rocking element relative to the angularly offset endportion 46 of the common terminal element 22 to permit movement thereofabout the point P1. In addition, the coil spring 70 is located beneaththe groove 52 of the L-shaped rocking element which defines the secondpivot point P2 of the movable contact assembly, causing the contactelement or button 60 to engage the fixed contact element 38 of theterminal element 20.

When the push button means S is depressed against the vertical componentof force of the spring 70, the L-shaped locking element is engaged andmoved downwardly causing pivoting or rocking thereof about the point P1.Downward movement of the L-shaped rocking element 42 also causesdownward movement of the groove 52 yand the movable contact blade 54mounted with respect thereto. As soon as the groove 52 passes a deadcenter position relative to the axis of the coil spring 70, the verticalupwardly directed component of the coil spring 70 will reverse directioncausing the contact blade 54 to pivot at point P2 creating an engagementbetween the contact element or button 60 and the fixed contact element36 of the terminal element 18. The relative position of the parts whenthis occurs is illustrated in FIG. 2 of the drawing, and will continueas long as the force is great enough to overcome the vertical componentof the coil spring at point P2. i

When the parts are in the position shown in FIG. 2, the circuit 1betweenterminals 20 and 22 will be opened with ya corresponding closing of thecircuit between terminals 18 and 22. When the pushbutton means S0 isreleased, the vertical force acting upon the L-shaped rocking element 42at point P2 causes the element 42 to pivot counterclockwise carryingblade pivot P2 back across the dead center position of the spring axisand transferring the movable contact blade 54 and its contact element orbutton 60 back to its normally closed position depicted in FIG. 1.

It is important to note that during the aforementioned movement of themovable contact assembly 40, a wiping action is imparted to the contactelement or button 60 as it moves between the xed contacts 36 and 38. Thewiping or sliding action of the movable contact element or button 60relative to the fixed elements 36, 38 serves to keep the contactsurfaces clean and insures breaking loose of stuck or welded contacts.The present construction provides an excellent contact wiping action dueto the horizontal component of force which is imparted to the blade 54not only as a result of its passing dead center position of the coilspring 70, but also due to the pivoting or rocking of the L-shapedrocking element 42. In other words, as the L-shaped rocking elementpivots about point P1, the blade pivot P2 will describe an arc aboutpoint P1,

and this Will permit a horizontal component or force to be derived bothfrom the rocking or pivoting action of the L-shaped rocking element 42as well as the movement of the contact blade 54 as it passes the deadcenter position of the coil spring 70.

As lanother important feature of the present invention, it will be notedthat the coil spring is not a current carrying element in the switchconstruction. While one end of the coil spring is anchored to the bightend portion 66 of the contact blade 54, the other end is anchored to thespring pivot pin 74 which is mounted to the insulated housing 12.Therefore, any current which is carried through the coil spring 70 willbe insulated by the housing 12. Current will thus be carried through themovable contact blade 54 and the L-shaped rocking element 42 to thecommon terminal element 22 which will have the effe't of increasing thecurrent rating of the instant switch.

The aperture 72 of the L-shaped rocking element 42 is suliciently largeto permit freedom of movement of the coil spring 70 throughout itsentire range of positions to preclude the possibility of mechanical orelectrical interference between the spring and the L-sh-aped rockingelement 42. This is important in insuring the intended performance ofthe various switch components such as the biasing characteristics of thecoil spring 70 without causing any arcing or interruption of the currentcarried by the L-shaped rocking element.

In the embodiment shown in FIGS. 1-3, the pushbutton means 50 comprisesan actuator button 76 and a manually depressible plunger element 78which extends through the housing 12 of the switch 10. The lower face ofthe actuator button 7,6 rests atop the curvilinear portion 48 of theL-shaped rocking element 42 while the upper face supports the manuallydepressible plunger element 78. It will be understood, of course, thatthe actuator button 76 Iand the plunger element 78 may be formedintegrally with one another to provide a one-piece pushbutton means ifthis is desired.

As best seen in FIG. 3 of the drawing, the actuator button 76 comprisesa U-shaped member having spaced leg portions 80, 82 which depend from aconnecting end portion 84. The distance between the spaced leg portions80, 82 of the actuator button 76 is such that they may be readilyreceived within notched areas 86, 88 respectively provided on oppositesides of the terminal element 18 for guiding the actuator button in apredetermined path as it is moved in the fashion previously describedbetween its uppermost and lowermost positions. The primary guide meansis, however, in the form of suitable lug elements 90 which may -beintegrally molded in the switch housing 12 in the vicinity of theactuator button 76 to guide it as it is moved between its uppermost andlowermost positions. The connecting end portion 84 of the actuatorbutton is designed to function as an overtravel limit stop to preventL-shaped rocking element 42 from traveling too far in a downwarddirection which would cause it to lose its reset moment. In thisrespect, it will be noted that the relationship of the connecting endportion 84 to the terminal element 18 when the parts are in the positionshown in FIG. 1 is such that the connecting end portion 84 will engagethe terminal element 18 to prevent further downward movement of theL-shaped rocking element 42 after the movable contact assembly has beenmoved to the position in FIG. 2 of the drawing.

Reference is now made to FIG. 4 of the drawing for a slightly modifiedform of the present invention. In this ligure, similar referencenumerals are employed with thc suffix a used to designate correspondingelements of the FIGS. 1-3 embodiment. The switch 10a is identical withthe switch previously described with the exception of the means forinitiating or causing movement of the movable switch componentsSpecifically, it will be noted that the plunger element 78a is offset toone side of the switch housing 12a with the lower surface thereofengaging the free end of a spring lever 90 mounted to the housing 12a.The spring lever 90 is received within a slot 92 of the housing 12a andconforms in conguration at 94 to the curvilinear ear portion 96integrally molded to the housing 12a to permit pivoting movement ordeflection of the spring lever at a point generally designated D1. Thespring lever 90 extends across the concavity of the housing 12a andengages the upper face of the actuator button 76a, the free end 98 ofthe housing being in turn engaged by the lower face of the depressibleplunger element 78a. It will be apparent that upon depressing theplunger element 78a, the spring lever 90 will deiiect or pivot abouthpoint D1 cauing the actuator button 76a to move downwardly to operatethe movable contact assembly 40a in the same manner as previouslydescribed. A certain amount of additional reset force is produced asthis lever is deflected or moved about point D1 which enhances the useof this particular embodiment tor very light force applications.

From the foregoing, it will now be appreciated that the presentinvention provides a snap action switch device which promotes excellentcontact wiping action while also having high current carryingcapability. The switch device can be operated in a reliable fashion byeither of the actuators illustrated in the drawing to provide thedesired switching operations for a variety of commercial uses.

Various embodiments of the invention have been shown herein, and it willbe understood that these are for illustrative purposes only. Variouschanges in structure will no doubt occur to those skilled in the art,and will be understood as forming a part of the invention insofar asthey fall within the spirit and scope of the appended claims.

I claim:

1. A single pole double throw snap action switch device comprising, aswitch housing having pushbutton means mounted for movement from anormal to a second position, a movable contact assembly engaged by saidpushbutton means and including a generally L-hsaped rocking elementpivotally mounted at a first portionthereof to a common terminal elementand having a second portion thereof positioned for engagement with saidpushbutton means, a movable contact blade pivotally mounted at one endthereof to said generally L-shaped rocking element and carrying at itsother end a contact element disposed between a spaced pair of lixedcontact elements each being electrically connected to a separateterminal element, each of said terminal elements being supported by saidhousing and positioned so that the common terminal element isintermediate the other terminal elements, spring means fixed at one endwithin said switch housing and at its other end to the movable contactblade for normally biasing the contact element of said movable contactblade against one of said fixed contact elements and for yieldablyurging said second portion of said generally L-shaped rocking elementagainst said pushbutton to hold it in its normal position, saidpushbutton means capable of being manually depressed for movement to itssecond position causing substantially simultaneous pivotal movement ofsaid L-shaped rocking element and said movable contact blade forovercoming the biasing effect of said spring means to provide a wiping'y effect of the contact element on said movable contact blade as it ismoved with a snap action between said fixed contacts, release of saidpushbutton means causing return of the switch components to their normalposition, one of said terminal members which are electrically connectedto a fixed contact element having at least one notched area forcooperating with at least one notched portion of said pushbutton topermit portions of said 1 pushbutton to move past said one terminalmember during the actuation and release of said pushbutton. 2. Theswitch device as dened in claim 1 wherein said pushbutton meanscomprises a pair of spaced leg portions, each of which contacts saidgenerally L-shaped rocking element. f 3. The switch device as defined inclaim 1 wherein the one end of the spring means which is fixed withinthe housing is insulated from all of said contact elements and thespring is engaged only at itsends.

4. The switch device as defined in claim 1 wherein all of said terminalelements extend externally of the same wall of the switch housing.

References Cited UNITED STATES PATENTS 3,233,057 2/1966 Aschwanden 2oo673,098,905 7/1963 Anderson. 3,157,759 11/1964 Kudaiis.

FOREIGN PATENTS 588,421 6/1965 switzerland. 1,024,155 l/1953 France.

ROBERT K. SCHAEFER, Primary Examiner.

DAVID SMITH, JR., Assistant Examiner.

